Optical recording medium substrate, optical recording medium, and method of manufacturing optical recording medium substrate

Abstract

There is provided an optical recording medium substrate including a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25° C. is in a range from 1.1930 g/cm 3 to 1.2000 g/cm 3 .

What is claimed is: 
     
         1 . An optical recording medium substrate comprising:
 a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25° C. is in a range from 1.1930 g/cm 3  to  1 . 2000  g/cm 3 .   
     
     
         2 . An optical recording medium comprising:
 an optical recording medium substrate which is a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25° C. is in a range from 1.1930 g/cm 3  to 1.2000 g/cm 3 .   
     
     
         3 . The optical recording medium according to  claim 2 , further comprising:
 a transparent cover layer on an information readout surface side of the optical recording medium substrate.   
     
     
         4 . A method of manufacturing an optical recording medium substrate, comprising:
 filling and injection-molding a polycarbonate in which an average molecular weight is in a range from 15000 to 16000 in a mold; and   performing cooling in the mold for 6 seconds or more.   
     
     
         5 . The method of manufacturing an optical recording medium substrate according to  claim 4 , comprising:
 forming a transparent cover layer on an information readout surface side of the optical recording medium substrate after extracting the optical recording medium substrate from the mold.